A method is proposed for encoding/decoding an image having rectangular blocks of pixels. The image has a height of H blocks and a width of W blocks and is divided into vertical (or horizontal) bands of blocks having the height of H (or width of W) blocks. The method includes: obtaining N processors and M coprocessors, the M coprocessors distributed over S levels, N>1, S>0 and M>S; assigning the N processors Pi to N contiguous bands BPi having sizes of Ki blocks, 0≦i≦N−1 and ∑ i = 0 N - 1 ⁢ ⁢ K i = W ; for every level of coprocessors s, 0≦s≦S−1, assigning Ms coprocessors CPs,j to Ms contiguous bands having sizes of Qs,j blocks, with: ∑ j = 0 M s - 1 ⁢ ⁢ Q s , j = W ; managing sending of first, second and third start messages, and first and second verification messages to the processors and coprocessors, according to a predetermined set of rules.